current_fruit (trunk only)

I almost abandoned this when Michael beat me to it, but besides
handling the fruit rename bug it also moves `current_fruit' into the
context structure to eliminate separate save/restore for that.

include/context.h

@@ -79,6 +79,7 @@ struct context_info {
 				/* 3: FH, 4: ff+, 5: ff-, 6: FF+, 7: FF- */
 				/* 8: travel */
 	unsigned startingpet_mid;
+	int	 current_fruit;	/* fruit->fid corresponding to pl_fruit[] */
 	int	 warnlevel;
 	int	 rndencode;	/* randomized escape sequence introducer */
 	long next_attrib_check;	/* next attribute check */